Health-care acquired pneumonia (HCAP) is a newly-recognized clinical entity which has a higher morbidity and mortality than community acquired pneumonia (CAP). Patients with HCAP are at risk for multi-drug resistant organisms due to past healthcare exposures such as recent hospitalizations, nursing homes, and dialysis units, and tend to have a high burden of co-morbid illnesses. The 2005 American Thoracic Society/Infectious Diseases Society of America guidelines recommend that patients diagnosed with HCAP be treated initially with 3 broad- spectrum antibiotics; however, the evidence behind these recommendations comes from several small observational trials. These studies show that compared to patients with CAP, patients with HCAP have higher mortality and are more likely to be treated with inappropriate initial antibiotic therapy, but it is not known whether widespread use of several broad-spectrum agents will improve patient outcomes. Because these antibiotics can cause serious side effects and are often expensive, physicians may be hesitant to prescribe according to the guidelines without more evidence of their comparative effectiveness. We will conduct a retrospective cohort study using highly detailed patient-level claims and microbiological data contained in the Perspective data warehouse (PREMIER Healthcare Inc.) from January 1, 2007 to December 31, 2008 from 550 participating hospitals in the United States. We will examine data from hospitalized patients = 18 years of age who were admitted with a diagnosis of pneumonia. The aim of our study is to determine whether patients hospitalized for HCAP have worse outcomes than those admitted for CAP, whether differences in outcome are due to co-morbid illnesses or to resistant organisms, and whether HCAP patients who are treated with the empiric antibiotic regimen recommended by the ATS-IDSA guidelines have better outcomes (lower mortality, fewer complications, shorter length-of stay and lower costs) than patients treated with other antibiotics. Our study will use sophisticated statistical methods, including logistic regression, propensity matching and an adaptation of the instrumental variable approach, to adjust for pre- treatment differences between patients and compare the effectiveness of different antibiotic regimens. Our results will help to guide physicians in the treatment of individual patients and aid experts in developing evidence-based clinical practice guidelines. Information we discover about physician practice patterns will also help quality officers and policy-makers identify areas for improvement in the care of this common and deadly illness. PUBLIC HEALTH RELEVANCE: Quality of Care and Outcomes of Healthcare-Associated Pneumonia will provide important insight into a clinical dilemma faced by physicians who care for as many as 300,000 patients each year with Healthcare-Associated pneumonia (HCAP). This study will assess whether patients with HCAP are receiving care consistent with the recommendations found in guidelines developed by the American Thoracic Society and the Infectious Disease Society of America, and whether those treated according to the guidelines have better outcomes than patients who are treated with other antibiotics. These results will help clinicians balance the potential benefits of the recommended antibiotics against the potential harms of antibiotic side effects, future antibiotic resistance, and increased costs. If recommended therapy is beneficial but underutilized, these results will alert quality improvement officers and policy makers to an important opportunity to improve patient care for a common and deadly illness.